Patent GB-542777-A (GB)
Title: Improvements in or relating to receivers for start-stop printing telegraph signals
IPC: H04L13/08
Filed: 1940-07-26
Abstract: 542,777. Type-printing telegraphy. CREED & CO., Ltd., and MASON, F. P. July 26, 1940. No. 12204. [Class 40 (iii)] In a start-stop printing-telegraph receiver, the signals are received and distributed by a continuously rotating distributer incorporating storage means for the incoming signals. The storage means may comprise a series of condensers, say 140, or a magnetic device comprising a large number, say 200, of armatures pivoted around a drum and co-operating with stationary setting and pick-up electromagnets. In the system shown in Fig. 1, the distributer comprises a drum containing condensers connected to segments engaged by brushes B1 ... B9, only a few of the condensers being shown. The drum rotates continuously at a speed roughly synchronous with that of the transmitter. The start signal is stored and subsequently initiates the simultaneous transfer of all the code combination signals to a translating device. The condensers C2 ... C7 are charged in sequence over brush B9 when the line relay RR receives spacing signals, all the condensers connected to segments passing under brush B9 during a spacing signal being charged. It is assumed that condensers C2 (and others near it but not shown) will be charged by the starting signal, and some of the condensers C3 ... C7 by the code signals. When condenser C2 reaches brush B6, brushes B1 ... B5 will each engage a condenser corresponding to one of the five code units. Condenser C2 energizes a gas-filled valve R6, thereby producing an impulse in the secondary of a transformer T6, which is connected to the primaries of transformers T1 ... T5 and thence through rectifiers MR1 ... MR5 to brushes B1 ... B5. The potential of any condenser C3 .. C7 that is charged will oppose the potential due to the impulse in transformer T6 but any uncharged condensers C3 ... C7 will be charged by such impulses, the impulses in the corresponding secondaries of T1 ... T5 energizing some of the gas valves R1 ... R5 controlling the selecting mechanism. The printing magnet PM is energized by valve R7 when the condenser C2 reaches brush B7, and the valve R6 is de-energized when condenser C2 reaches brush B8, thereby energizing valve R8 which extinguishes R6. In the system shown in Fig. 7, the distributer comprises a drum carrying say, 200 armatures pivoted at c, Fig. 3, with two positions a and b. The armatures are moved into positions a or b by current in windings M1 or M2 controlled by the line relay LR and subsequently influence pick-up magnets M3 ... M10, Figs. 6, 7, spaced around the drum. The pick-up magnets may be shaped as in Figs. 3 and 4, and have their poles slightly staggered so as to bridge opposite ends of two adjacent armatures, so that if the two armatures are in the same position a small flux passes but if they are in opposite positions a large flux passes. Thus an impulse is produced in the magnet winding when adjacent armatures are in different positions, i.e. when a point on the drum corresponding to a signal transit passes under the magnet. If a prolonged stop signal is being received, magnet M2 is energized and the armatures are deflected to position b. Upon the arrival of a start signal, magnet M1 moves the following armatures to position a, the following code signals deflecting armatures to positions a or b according to their polarity. When the armatures set by the start signal reach magnet M8, an impulse produced therein energizes gas valve R6 and de-energizes valve R9, thereby increasing the potential on conductor C thus decreasing the bias on the grids of gas-filled valves R1 ... R5 so that certain of these are energized by the impulses produced in magnets M3 ... M7 as the corresponding sets of armatures pass them. When the armatures set by the start signal reach magnet M9, valve R8 is energized and de-ionizes valve R6. The start signal is re-recorded by a second armaturesetting magnet M11, M12 in the anode circuits of valves R6, R8; the magnet M11, M12 also obliterates all other signals so as to prevent them from energizing valves R7 or R9. The printing magnet PM is energized by valve R7 when the re-recorded start signal passes magnet M10. Modifications of this system are described. Specification 526,833 is referred to.